Churchill said- "In war, one has neither friends nor enemies, only interests".
The Japs bombed Darwin, so it was in the interest of Australia to join Britain in fighting the Japs in the Far East, and Oz also sent troops to North Africa to help protect the Suez canal which was the main supply link between Britain and Australia.
If in the future, Muslim Indonesia with its 323 million population decides to hop across the Timor Sea and invade an independent Australia (pop only 22 million) there'll eventually be mosques all the way from Darwin to Tazzy, and all the sheilas and female roos will be forced to wear burkas.
But if Oz chooses not to go independent and instead maintain ties with Britain, Britain will of course help to sink any Indonesian invasion fleet.
Britain (pop 60 million) has nuclear weapons, but Australia doesn't.
That fact alone should make every Australian citizen think twice before shouting about cutting ties with the powerful Poms, we hit big..
As for Oz turning to the Yanks for help in time of a future war, why would it be in Americas interest to help? Why should they?
Remember it took them 2 years before deciding to join WW2 and that was only because the Japs bombed Pearl, and as Britain was already fighting the Japs, America came in to help because it was in her interest.